In recent years it has become commonplace for beers to be chilled and served at a temperature close to but above zero ° C.
To enhance the illusion of a really chilled beer it is also commonplace for beer to be dispensed through a font which is itself cooled sufficiently that ice forms on the outside of the font.
Where beer is cooled close to zero there can be a diminution in the flavour of the beer as well as a reduction in the head of froth when it is poured, all of which tends to make it visually less appealing to the consumer.
Where a really cool drink is required it is difficult to preserve the characteristics of normal beer as the beer temperature is reduced and, in particular, if ice is added to the beer the flavour of the beer is diluted. This can be avoided to a certain extent by using frozen beer as ice, however the freezing process expels the beer flavour to the exterior of the ice crystals so that the effect is once again of ice crystals floating in the resultant drink.